Signal conversion apparatus for use in PCM signal processing system

Abstract

A signal conversion apparatus for use in a PCM signal processing system in which a series of multi-bit digital signals is produced through sampling and quantization of a multi-channel analog signal. The series of multi-bit digital signals includes groups of multi-bit digital signals being representative of respective analog signal portions constituting the multi-channel analog signal. The apparatus comprises a translating section for producing substitutional multi-bit digital signals from at least one of the groups of digital signals corresponding to at least one analog signal portion, which substitutional digital signals represent amplitudes of the one analog signal portion at sampling points different from those at which the one analog signal was sampled to provide the one group of digital signals. The substitutional digital signals are substituted, in the translating section, for the one group of the digital signals to produce a corresponding group of sampling point-shifted multi-bit digital signals. The resulting PCM multi-bit digital signals are acceptable by digital-to-analog conversion processor requiring PCM digital signals generated through sampling at shifted or different sampling points as compared with the above-mentioned series of digital signals.

We claim: 
     
       1. An apparatus for converting a multi-channel analog signal to a PCM signal, said multichannel analog signal including a plurality of analog signal portions on separate channels, the apparatus comprising: means for converting all of said analog signal portions to multi-bit digital signals through sampling and quantization, each of said digital signals being representative of the amplitude of different one of said analog signal portions at a sampling point during said sampling; and   translation means coupled to said converting means for producing from at least those of said multi-bit digital signals which correspond to at least one of said analog signal portions substitutional multi-bit digital signals representative of the amplitudes of said at least one analog signal portion at sampling points different from those at which said at least one analog signal portion was sampled to provide said those multi-bit digital signals and substituting said substitutional digital signals for a part of said those digital signals corresponding to said at least one analog signal portion.   
     
     
       2. An apparatus according to claim 1, in which said converting means includes a plurality of converters, the number of said converters being the same as that of said channels so that each of said analog signal portions is converted to a group of multi-bit digital signals in its associated one of said converters, said translation means is arranged to receive the output of that one of said converters which deals with said at least one analog signal portion, and the apparatus further comprises means coupled to receive the output of said translation means and the outputs of said converters except said that converter for multiplexing them to produce said PCM signal. 
     
     
       3. An apparatus according to claim 1, in which said converting means includes a plurality of converters, the number of said converters being the same as that of said channels so that each of said analog signal portions is converted to a group of multi-bit digital signals in its associated one of said converters, the apparatus further comprises means coupled to said converters for multiplexing the outputs of said converters to produce a series of multi-bit digital signals and means for selecting from said series of digital signals a group of multi-bit digital signals being identical with said those digital signals, and said selecting means is connected between said multiplexing means and said translation means. 
     
     
       4. An apparatus according to claim 1, in which said converting means includes a single converter and multiplexing means for said conversion to said multi-bit digital signals and for producing therefrom a series of multi-bit digital signals, and the apparatus further comprises means for selecting from said series of multi-bit digital signals said those multi-bit digital signals, said selecting means being connected between said converting means and said translation means. 
     
     
       5. An apparatus according to claim 1, in which said translation means is constituted by a digital filter. 
     
     
       6. An apparatus for converting a PCM signal to a multi-channel analog signal including a plurality of analog signal portions on separate channels, said PCM signal containing a series of multi-bit digital signals representative of said multi-channel analog signal, the apparatus comprising: translation means for producing from at least those multi-bit digital signals in said series of multi-bit digital signals which correspond to at least one of said analog signal portions substitutional multi-bit digital signals representative of the amplitudes of said at least one analog signal portion at sampling points different from those at which said at least one analog signal portion was sampled to provide said those multi-bit digital signals and substituting said substitutional digital signals for a part of said those digital signals corresponding to said at least one analog signal portion; and   means arranged for receiving the remaining multi-bit digital signals and coupled to said translation means for thereby converting said remaining multi-bit digital signals and the output of said translation means to said analog signal portions on separate channels.   
     
     
       7. An apparatus according to claim 6, further comprising means for selecting from said series of multi-bit digital signals said those mutli-bit digital signals, the output of said selecting means being coupled to said translation means for the production of said substitutional multi-bit digital signals in said translation means, said converting means includes a single converter for receiving the output of said translation means and means connected with said single converter for separating its output into said analog signal portions on different channels. 
     
     
       8. An apparatus according to claim 6, in which the apparatus further comprises means for separating said series of multi-bit digital signals into groups of multi-bit digital signals, each of said groups being representative of different one of said analog signal portions, said converting means includes a plurality of converters, the number of said converters being the same as that of said channels so that each of said groups of multi-bit digital signals is converted to an analog signal portion in its associated one of said converters, said translation means being connected between said separating means and that one of said converters which deals with said those multi-bit digital signals. 
     
     
       9. An apparatus according to claim 6, in which said translation means is constituted by a digital filter.